Refractory muffle



March 6, 1928.

C. W. SAXE REFRACTORY MUFFLE Filed July 5. 1926 m M Wm 5 W M a h C Wilinsuea Patented Mar. 6, 1928.

.UNITED STATES PATENT OFFICE.

CHARLES W. SAXE,'OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO N ORTOI N' COM- PANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

nnrnac'ronx nor-rm.

Application filed July 8,

v This invention relates to structures employed as mufiles or as combustion chambers in furnaces and particularly to that type of mufile or combustion chamber described in o the U. S. patent to Meehan No. 1,348,511 and referred to throughout this specification as a-mufile structure.

It has been common heretofore to make structures of this type from a refractory granular material, such as silicon carbide or fused crystalline alumina, united by an'appropriate ceramic bond. In accordance with this practice the granular material is mixed with the required amount of a suitable ceramic bond, such as fire clay, together with a fluid, such as water, to impart the desired plasticity to the mass. The plastic mixture is then carefully placed in a cored plaster mould and permitted to dry, 0 after which the moulded article is removed and fired to vitrify the bond. This method of manufacture not only has been extremely difiicult but has been very expensive. Furthermore, muflles manufactured in this man- 26 ner have been subject to warpage during firing causing strains to be set up in the structure which often result in breakage.

It is the object of the present invention to provide a mufile of simplified construction which may be manufactured at small cost and which is suitable for high temperature operations.

It is another object to provide a muflle construction in which the top and bottom plates are interchangeable as well as the plates forming the side walls of. the muflie thereby reduclng the number of differently shaped plates to a minimum.

In accordance with the invention a muflle is provided by assembling dense refractory plates constructed so thatthe plates for the top and bottom portions are interchangeable and have a length equal to the width of the finished structure, and the interchangeable plates for the side portions extend between the top and bottom-portions and are held by the bottom portion and support the top portion. Each 'plate is provided with a relatively large engaging surface contaimng a tongue or groove so that the plates may be fitted together to form self supporting integral mufile walls. Preferably, the refractory plates, are made of a dense structure by tamping with considerable pressure 192G.'- Serial No. 120,466.

prior to vfiring the articles to vitrify the bond.

The invention will be more clearly understood from the following description in conjunction with the accompanying drawing: in which, I

F ig. 1 is a perspective view of the structure of the invention;

Fig. 2 is a detail perspective view of a plate employed in the side portions of the structure;

Fig. 3 is a detail view in perspective of a plate employed in the top or bottom portions of the structure; and

Fig. 4 is a sectional elevational view of a. furnace embodying the structure of the invention. a

In the drawing, a structure is illustrated embodying the invention comprising a plurality of dense, fiat refractory plates formin 'the bottom portion 10 carrying a plura ity of interchangeable verticall positioned plates of similar material fbrming side portions 11 which support a plurality of plates of refractory'materialforming the top portion 12. The bottom and top portions of the structure are interchangeable and are formed by interfitting a plurality of plates 13 having a length equal to the width of the finished structure. A groove 14 is formed in one longitudinal edge of the plate and a tongue 15 is provided upon the opposite longitudinal edge and is constructed and arranged to engage the groove '14 of any similarly constructed plate.

The flat face of the plate 13 is provided with a lateral groove 16 arranged to receive a tongue 17 on the relatively wide flat edge 18 of a refractory plate 19. One of the lateral edges of the plate 19 is provided with a groove 20 and the other is providedwith a tongue 21 so that a pliuality of the plates may be fitted together to form the side portions 11. The bottom portion of the structure is formed by interfitting a plurality of the plates 13 by engagement of the tongue 15 with the groove 14 on the next adjacent y forcing the tongue 21 into the groove'20 in the next adjacent plate, and as thus assembled are placed upon the bottom portion 10 so that the tongues 17 maybe forced into the grooves 16. The top portion 12 is then formed by interfitting a p urality of plates plate. The plates 19 are then fitted together 13 by engagement of the tongue 15 with the groove 14 of adjacent plates, and as thus assembled is placed in position upon the structure so as to bring the tongues 17 on the plates 19 into engagement with the grooves 16 upon the plates 13. In this manner a self-supporting structure is produced which is adapted to effectively resist the heat changes to which a mufii'e is normally subjected.

The refractory plates 13 and 19 may be made of any suitable refractory material, such a silicon carbide or crystalline fused alumina. This material is mixed with a suitable vitrifiable ceramic bond and an amount of water just sufiicient to impart moldability to the mixture. The mixture is then'placed in a suitable mold and tamped with considerable pressure or impact. The molded article is then removed and dried before placing in a kiln or firing to vitrify the bond. I

The structure of the invention may be employed either as a combustion chamber or as a muflle'in a furnace construction, such as is diagrammatically illustrated in Fig. 4, comprising a floor 25 and sidewalls 26 which support a top 27, theends being closed by a door or end wall 28. The structure of the invention may be placed within the furnace so that it rests above the floor 25 preferably with the bottom portion supported,

' as by pillars29, so as to provide free circulation of heat or gases around the structure.

In practice, the furnace may be fired by the combustion of fuel within the furnace but outside of the muflle so that the gases will not come directly in contact with the contents within this structure. So also, the firing conditions may be reversed and the structure of the invention may be employed as the combustion chamber in which the fuel is burned to transmit heat to the other parts of the furnace.

The invention provides a mufile of simple construction which may be manufactured at a low cost, and while it is composed of a lurality of separate sections, nevertheless,

1t is self-supporting and will not warp apwarpage.

preciably under normal conditions of high temperature operations.

Staggering of the edges of adjoining plates assists in preventing dlStOltZOIl and The provisions of the invention permit the building of relatively long muflles, and if any of the plates become overheated they may be easily replaced.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent-is:

1. A refractory muflie structure for use in high temperature furnace operations comprisinga plurality of fiat dense refractory plates having a length equal to the width of the structure and provided with tongues and grooves interfitting to form continuous top and bottom walls of the muflie, and a plurality of plates of similar material ex tending between the top and bottom which are provided with tongues and grooves interfitting to form the muflie sides, said side plates being arranged upon the bottom plates and ada ted to support the top plates and provide with wide flat edges containing tongues adapted to engage i grooves in the inner fiate surfaces of the top and bottom plates, thereby providing an inte ral self supporting structure adapted to e ectively resist the heat changes encountered, in high temperature operations.

2. A refractory muflie structure for use in high temperaturefurnace operations comprising a pluralit of interchangeable flat dense refractory p ates forming the top and bottom of the muflle, and interchangeable side plates supported on the bottom plates and in turn supporting the top plates, each of the top and bottom plates extending the full width of the mufiie and the side plates extending between the top and bottom of the mufile, said plates having interfitting tongue and groove connections to form self supporting muflle walls.

Signed at- Worcester, Massachusetts, this 1st day of July, 1926.

CHARLES w. SAXE. 

